The invention relates to a proximity switch comprising a bearing body with a bearing opening, a sensor head having a proximity sensor with a sensor circuit arranged therein, a bearing attachment piece held on the sensor head and mounted in the bearing opening for rotation about an axis, and a plug connection having a connection side arranged on a side of the bearing attachment piece opposite the sensor head and comprising a connection sleeve and a contact insert arranged in the connection sleeve.
Such proximity switches are known, for example, from DE 196 18 664. In this solution, the connection sleeve is held rotatably in the bearing attachment piece.
However, such rotatability of the connection sleeve is problematic when screwing on a coupling nut.
The object underlying the invention is therefore to so improve a proximity switch of the generic kind that a plug connector is connectable to the plug connection in a way which in terms of ergonomics is as suitable as possible.
This object is accomplished in accordance with the invention in a proximity switch of the kind described at the outset in that the connection sleeve is non-rotatably held in the bearing attachment piece, and in that the contact insert is mounted in the connection sleeve for rotation relative thereto.
The advantage of the inventive solution is to be seen in the fact that owing to the rotatability of the contact insert a plug connector connectable to the plug connection can be expediently aligned in an advantageous way. In particular, the alignment of the cable relative to the bearing body is possible in a simple way. On the other hand, it is possible to tighten the coupling nut on the connection sleeve in a simple way without the connection sleeve itself having to be held firmly as the connection sleeve is not rotatable relative to the bearing attachment piece.
In order to prevent turning of the cables leading to the contact insert to too great an extent owing to the rotatability of the contact insert relative to the connection sleeve and hence occurrence of a fault, provision is preferably made for the contact insert to be mounted for limited rotation relative to the connection sleeve.
The contact insert is preferably rotatable through an angle of 360xc2x0 or less than 360xc2x0 relative to the connection sleeve.
In the above explanation of the inventive solution no further details were given as to the design of the contact insert.
In a particularly advantageous embodiment, provision is made for the contact insert to comprise a protective sleeve which extends from a contact support in directions opposite to one another. The advantage of such a protective sleeve is to be seen in the fact that a high safety class is thereby achievable in a simple way, i.e., large leakage distances and clearance distances (air distances) and hence high protection against leakage currents (creeping currents).
Provision is preferably made for the protective sleeve to form a plug connection protective section which encloses plug connection sections starting from the contact support.
Furthermore, an advantageous embodiment makes provision for the protective sleeve to comprise a cable connection protective section which encloses cable connection sections.
A particularly advantageous embodiment makes provision for the protective sleeve to extend substantially over the entire extent of the connection sleeve in the direction of the axis.
A particularly expedient design of the protective sleeve, which offers considerable protection against leakage currents, makes provision for the protective sleeve to extend from the sensor head through the bearing attachment piece as far as the connection side. An extensive electrical protection of the electric contacts provided in the contact insert is thereby made possible.
For assembly of a proximity switch according to the invention it has proven particularly expedient for the contact insert to be inserted into the connection sleeve from a side opposite the connection side as a fixing can then be carried out in a simple way from one and the same side.
Provision is preferably made for the contact insert to be supported on the connection sleeve against movement in the direction of the connection side.
Such a supporting of the contact insert is preferably effected via its protective sleeve.
The supporting via the protective sleeve can be implemented via the plug connection protective section and/or via the cable connection protective section of the protective sleeve.
One possibility of fixing the contact insert consists in fixing it in the bearing attachment piece by securing elements such as, for example, a snap ring or a securing pin.
However, a particularly expedient solution makes provision for the contact insert to have a supporting flange which is supported on the sensor head. A particularly simple support against movement in the direction of the sensor head and hence a fixing of the contact insert in the direction of the axis is thereby achievable by the assembly of the sensor head.
The contact insert itself can be implemented in different ways. It is conceivable to anchor contact pins directly in the contact support of the protective sleeve.
The contact support may be removable from the protective sleeve so as to connect cable ends with the cable connection sections of the contact pins.
A particularly expedient solution makes provision for the contact support to be integrally connected to the protective sleeve.
In this case, it is particularly expedient for the contact pins to be held on a contact pin carrier which, in turn, is insertable into the protective sleeve.
To obtain a non-rotatable connection between contact pins and protective sleeve it is particularly expedient for the contact support of the protective sleeve to comprise contact pin openings for passage of the contact pins therethrough.
To ensure a tight closure in the area of the contact pins and the contact pin carrier, the opening of the protective sleeve receiving the contact pin carrier is preferably at least partly cast with molding compound.
A wide range of possibilities is conceivable for implementing the connection sleeve.
For example, it is possible to design the connection sleeve as a part which is integral with the bearing attachment piece. However, a particularly expedient solution makes provision for the connection sleeve to be a separate part inserted into the bearing attachment piece.
In principle, it is also conceivable to insert the connection sleeve into the bearing attachment piece from a side opposite the sensor head. However, a particularly expedient solution makes provision for the connection sleeve to be inserted into the bearing attachment piece from a side opposite the connection side.
It is particularly expedient for the connection sleeve to be supported by stop devices against movement in the direction of the connection side.
However, in order to hold the connection sleeve in this position it is also necessary to additionally fix the connection sleeve. Such a fixing could also be implemented by supplementary means such as, for example, a snap ring or a securing pin.
It is, however, particularly expedient for the connection sleeve to be held by the contact insert in a defined position relative to the bearing attachment piece against movement in the direction of the sensor head.
This can be implemented in a particularly simple way by the connection sleeve being acted upon by the protective sleeve of the contact insert.
By fixing the contact insert in the direction of the axis about which the bearing attachment piece is rotatable relative to the bearing body, both the connection sleeve and the contact insert can therefore be fixed in the direction of this axis in a simple way.
It is expedient for both the connection sleeve and the contact insert to be supported via the contact insert against movement in the direction away from the connection side.
This supporting is preferably implemented via the supporting flange.
A particularly advantageous solution makes provision for both the contact insert and the connection sleeve to be secured against movement away from the connection side by fixing the supporting flange on the sensor head side. A particularly expedient embodiment of the inventive solution makes provision for the sensor head to have a support which is connected to the bearing attachment piece and on which a sensor head housing is positionable in at least two positions having between them an angle of 180xc2x0 which is determined relative to an axis of symmetry of the support extending at an incline to the axis of rotation of the bearing attachment piece. The sensor head is capable of orientation in two different directions, namely, on the one hand, a detection direction in the direction of the axis of rotation and, on the other hand, a detection direction transverse to the axis of rotation.
Very different possibilities are also conceivable for fixing the bearing attachment piece in the bearing opening.
A particularly expedient solution makes provision for the bearing attachment piece to have a circumferential securing groove with which a securing element fixable on the bearing body is engageable.
Such a securing groove thus allows securing of the bearing attachment piece against movement out of the bearing opening in the direction of the axis.
A wide range of possibilities is conceivable for fixing the bearing attachment piece in individual rotary positions relative to the bearing body. It is, for example, conceivable to provide toothings.
However, a particularly expedient solution makes provision for the bearing attachment piece to have flat areas which cooperate with fixing elements provided on the bearing body.
A particularly advantageous embodiment of such a fixing element makes provision for it to be designed as an adjustable pressure element which is advanceable in the direction of the flat area so as to non-rotatably fix the bearing attachment piece in the bearing opening.
As a supplement or alternative thereto, a further advantageous embodiment makes provision for the fixing element to be arranged on a detent spring element.
Such a detent spring element is preferably designed as a resilient detent tongue.